Like many invasive cell-populations fungi need to fine-tune their mechanical and morphological properties, in response to different environmental signals, for pushing through their substrates to meet their metabolic and functional needs. Monitoring these properties in real-time in 3D is critical for identifying the molecular mechanisms that drive their invasions, and discovering novel modulatory molecules that change their invasiveness for the benefit of humans. Although light microscopy through its great progress in recent years has uncovered many local cellular events at nanometer resolution, visualizing global changes in morphology of cell colonies growing on and into their substrates with precision, is extremely challenging and often involves sample preparation that require cells to grow in conditions very different from their native growth conditions. Also mapping and quantifying mechanical properties of cell-populations in parallel with monitoring global morphology is very difficult because such properties cannot be visualized. The most popular methods to determine mechanical stress and viscoelastic properties within a micrometer or nanometer scale in live cells include localized aspiration of cytoplasm, magnetometry, and atomic force microscopy (AFM), where cells are perturbed by an external force and then the strains are mapped to determine the cell properties. However, for colonies with mostly non-synchronous metabolically diverse cells, as in fungal colonies, such local measurements will be incapable of providing an accurate reflection of the global morphomechanical behavior of the colony.
The goal that remains therefore, is a minimally-invasive technique that can provide accurate information of the mechanical and the morphological features of an entire landscape of a cell population.